Cleaning apparatus for contaminated gasses

ABSTRACT

Gas-cleaning apparatus comprises a gas inlet port, a demister, a discharger port, and at least one liquid film-forming screen and liquid spray means disposed between the inlet port and screen, whereby gas passes through the liquid film-forming screen.

United States Patent Masao Yokoi Tokyo;

Kiyoshi Uyalna; Kenji Indo; Yoshiyuki Nakai; Tetsuya Yokogavva, Yokohama-shi, all of Japan Feb. 24, 1969 Nippon Kokan Kabushiki Kaisha Chlyoda-ku, Tokyo, Japan Mar. 1, 1968 Japan Mar. 1, 1968, Japan, No. 43/15471 Inventors Appl. No. Filed Assignee Priorities CLEANING APPARATUS FOR CONTAMINATED GASSES 2 Claims, 8 Drawing Figs.

US. Cl 261/23, 261/97, 261/105, 261/106, 261/117, 55/258,

55/259 Int.Cl B0ld 47/12 Field of Search 55/258,

[56] References Cited UNITED STATES PATENTS 655,285 8/1900 Thomas 55/259 1,286,550 12/1918 Davis 261/106 X 1,471,112 12/1919 Ellis 55/258X 1,813,692 7/1931 Anderson. 55/258 X 1,841,536 1/1932 Jordahl 261/97 2,158,294 5/1939 Long 261/106 X 2,529,839 11/1950 Garvey et al.. 261/106 2,833,122 5/1958 Kohlet a1. 55/258 X 2,998,059 8/1961 Johnson 55/258 Primary Examiner-Tim R. Miles Assislan! Examiner-Steven H. Markowitz Auorney Flynn & Frishauf ABSTRACT: Gas-cleaning apparatus comprises a gas inlet port, a demister, a discharger port, and at least one liquid filmforming screen and liquid spray means disposed between the inlet port and screen, whereby gas passes through the liquid film-forming screen.

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PATENTEDUEC new 7 36255491 SHEET 3 [1F 4 BACKGROUND OF INVENTION This invention relates to an improved cleaning apparatus for contaminated gas such as high-temperature exhaust gas from blast furnaces and the like, and more particularly to an improved cleaning apparatus wherein contaminated gas is passed through liquid films on a screen whereby to cool and clean high-temperature exhaust gas.

According to a prior art apparatus of the type referred to above there is provided a vertical cylinder having an inlet for the contaminated gas at the lower center portion thereof. A diverting duct is connected to the inlet to uniformly divert the gas from the axis of the cylinder toward the outside thereof. The diverting duct is surrounded by a cylindrical screen including a mesh or a plurality of small openings of a size sufficient to form a liquid film and the screen is partitioned by baffle plates which permit the flow of gas. Concentric cylinders are provided with a definite spacing. The upper portion of the screen is connected to a slit passing a liquid whereby to form a liquid film on the screen by the continuously flowing down liquid. By passing exhaust gas through the screen, gas is cleaned at a high efficiency. However, this construction is disadvantageous in that it is not only difficult to fabricate but it is difficult to replace corroded screens.

Further, the size of the openings of the screen provided for the purpose of forming the liquid film is selected to be small in order to increase the cleaning effect through openings. These openings have a tendency to be clogged by contaminants or particles contained in the gas, thus causing a detrimental effect to the formation of a stable liquid film. Further, it is necessary to inspect and exchange the cylindrical screen to remove contaminants. For these reasons, it is highly desirable to provide a compact and rigid gas-cleaning apparatus which is easy to fabricate and repair.

It is therefore an object of this invention to provide an improved gas-cleaning apparatus for contaminated gas which is compact and simple in construction and capable of effectively removing gaseous or solid contaminants contained in the gas.

A further object of this invention is to provide an improved gas-cleaning apparatus which is provided with a demister at the outlet port of the cleaned gas to remove mist.

SUMMARY OF THE INVENTION Briefly stated, in accordance with one aspect of this invention there is provided a cleaning apparatus for contaminated gas comprising an inlet port for the contaminated gas, said inlet port being provided through a wall of the apparatus, a discharge port and a demister on another wall, the discharge port communicating with the interior of the apparatus through the demister, at least one liquid film-forming screen removably mounted at the center of the apparatus and liquid spray means disposed between the inlet port and the screen.

According to another aspect of the invention, a gas cooling chamber including liquid sprays and dust removing screens is disposed at the bottom of the gas-cleaning apparatus and a pair of spaced-apart screens are disposed above the gas cooling chamber, so that after washing and removal of solid particles, the gas flows upwardly from the gas cooling chamber, then inwardly to the central portion of the apparatus through liquid films on screens and is finally discharged out of the apparatus through a demister mounted at the top center of the apparatus.

BRIEF DESCRIPTION OF THE DRAWING FIG. I shows a sectional view of one embodiment of this invention;

FIG. 2 shows a front view of the apparatus shown in FIG. 1;

FIG. 3 is a top plan view of the apparatus shown in FIGS. I and 2;

FIG. 4 is a partial view to show the mounting of the screen spacers;

FIG. 5 shows'a sectional view of a modified embodiment of this invention;

FIG. 6 is a vertical sectional view taken along a line VI-VI in FIG. 5;

FIG. 7 is a top plan view of the modification shown in FIG. 6; and,

FIG. 8 is a partial view to show the mounting of the screen spacers utilized in the modified embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIGS. 1 to 4 of the a accompanying drawing which illustrate one embodiment of this invention, gas to be cleaned is admitted into a gas cooling chamber 3 of a gascleaning apparatus 2 through an inlet port I through one sidewall. In the gas cooling chamber are installed cooling water pipes 4 at three different levels. Each cooling water pipe is provided with a plurality of spray nozzles to spray water to cool the gas admitted in the gas cooling chamber and to remove contaminants from the gas whereby nearly all of soluble gas compositions such as $0 and dust entrained in the gas are removed.

The gas is then caused to pass perpendicularly through a liquid film-forming screen 5 provided substantially at the center of the apparatus 2. The screen comprises several sheets of metal wire netlike members, the number of the members being increased or decreased in accordance with the quantity and composition of the gas. As shown in FIG. 4, spacers 6 are interposed between adjacent netlike members to maintain a constant spacing between adjacent members. The spacers and netlike members are removably fabricated. A liquid tank 7 is removably mounted above screen 5 to form liquid films on the screen. The liquid is supplied to the screen through a manifold with a plurality of nozzles and is drained to the outside of the apparatus through a discharge conduit 8.

To reduce the quantity of water used, the exhausted water may be supplied again to water tank 7 after passing through a suitable filter (not shown).

More than 99.5 percent of SO, contained in the gas can be removed by the liquid film-forming screen 5. After passing through screen 5, the gas flows toward the right-hand end of the apparatus and is then discharged out of the apparatus through a discharge port 10 and through a demister 9 packed with glass wool and the like and which is provided at the top of the apparatus to remove white fumes, mist or the like.

In the modified embodiment shown in FIGS. 5 to 8, gas is admitted into a gas cooling chamber 13 at the lower center of the cleaning apparatus 12 through a gas inlet opening 11. On the opposite sides of the gas cooling chamber are disposed a pair of cooling water pipes 14, each provided with a plurality of vertically extending pipes 15 having a plurality of spray nozzles to spray liquid to cool the gas and remove contaminants therefrom.

From the gas cooling chamber the gas flows upwardly along opposite sidewalls as shown in FIG. 6. Water supplied from water tanks 26 and 27 at the top of the apparatus forms water films on liquid film forming screens 16 to 2! inclusive to completely remove contaminants from gas. There are also provided metal wire nets 22 and 23 in the passages of the gas. As a result nearly all of soluble gas compositions such as S0, and dust entrained in the gas are removed by the water spray and dust removing metal wire nets.

After passing through the metal wire nets the gas is deflected upwardly by the sidewalls of the apparatus 12. Then the gas flows inwardly to the center of the apparatus through liquid forming screens 16 through 21. Water collectors 30 and 30' are provided at the lower ends of respective screens. While three stages of screens supported by beans 28 and 29 are shown in the drawing, the number of stages may be varied dependent upon the quantity of the gas being treated and physical dimensions of the apparatus. Each of the screens comprises from 3 to 30 sheets of metal wire nets which are removably fabricated with spacers 24 interposed between adjacent wire nets, the number of wire nets being variable dependent upon the composition and flow quantity of the gas. Above the screens are removably mounted said water tanks 26 and 27 to supply water to screens 16 through 21 through nozzles. The major portion of the water falling into the bottom of the apparatus is discharged through a discharge pipe 31 and a portion of the water is discharged through a second discharge pipe 32 after passing through dust-removing wire nets 22 and 23.

Again the discharged water may be supplied again to water tanks 26 and 27 after passing through a suitable filter, not shown.

More than 99.5 percent of SO, contained in the gas can be removed by the water films formed on the screens. After passing through these screens, gas in the central portion of the apparatus is discharged through a gas outlet port 34 and through a demister 33 packed with glass wool and the like.

ln both embodiments, as the cleaning liquid either river or sea water can be used. To wash factory exhaust gas containing acidic gasses, ammonia water and the like can be added to the liquid to render it a weak alkaline solution. It is also advantageous to use stainless steel to construct members subject to severe corrosion. In the illustrated example, although one liquid tank is mounted on each side of the top of the apparatus, where the number of screens used is increased, the number of water tanks may be increased to more than two on each side. Further, it is also possible to supply different types of water, for example, plain water and water incorporated with ammonia, to difi'erent water tanks. Thus, this invention provides an improved cleaning apparatus of simple and compact construction which can effectively clean and cool hightemperature gas. Moreover, fabrication, replacement, maintenance and inspection of the screens can be made very easily. The provision of the demister assures complete removal of the mist contained in the cleaned gas.

While the invention has been shown and described in terms of preferred embodiments, it will be clear that many changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. Cleaning apparatus for contaminated gas comprising:

a gas cooling chamber at the bottom of said apparatus and including an inlet port to said chamber provided at the lower portion of said apparatus;

a pair of opposed liquid spraying means on opposite sides of said gas cooling chamber, said spraying means including liquid spray nozzles; and

a pair of dust-removing means on the opposite sides of said gas cooling chamber;

a plurality of of spaced-apart screens mounted in said apparatus above said gas cooling chamber, each of said screens including a liquid collector at its lower end, said plurality of pairs of screens being removably mounted in several stages; and

a demister mounted at the top of the central portion of said apparatus;

whereby said contaminated gas flows upwardly from 'said gas cooling chamber, then inwardly through said screens to the central portion of the apparatus and is finally discharged through said demister.

2. Apparatus according to claim 1 including independent liquid tanks mounted on the top of said apparatus above said screens to supply liquid to form liquid films on said screens.

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2. Apparatus according to claim 1 including independent liquid tanks mounted on the top of said apparatus above said screens to supply liquid to form liquid films on said screens. 